THIS invention relates to a silencer for a motor vehicle.
Free flow exhaust systems are widely used in the motor industry as they tend to improve the performance of a motor vehicle when compared to conventional exhaust systems. A drawback associated with free flow exhaust systems, however, is that the exhaust noise levels are considerably higher than for conventional exhaust systems, and are often higher than legal limits.
Attempts have been made to provide silencers or mufflers to reduce the noise of free flow exhaust systems to acceptable levels. Traditionally, this has entailed providing an elongate silencer which is positioned around a perforated section of the exhaust pipe to dampen the noise levels. As with conventional silencers, these free flow exhaust silencers are made from stainless steel or similar metallic materials. As a result, they generally have to be fitted by specialist fitters. They are also susceptible to corrosion and generally have to be replaced fairly often.
According to the invention a silencer includes a polymeric casing connected to at least one inlet pipe and to at least one outlet pipe by polymeric spacers.
The polymeric spacers are preferably heat-resistant, preferably have a higher melting point than the polymeric casing, are preferably made of a different material to that of the polymeric casing, are preferably flexible relative to the polymeric casing and are preferably softer than the polymeric casing.
The polymeric spacers are capable of deformation to accommodate irregularities in the shape of the inlet and/or outlet pipes.
The inlet and outlet pipes are preferably made of metal which is preferably steel.
The casing preferably has collars, with the polymeric spacers being located between the collars and the inlet and outlet pipes. The housing preferably narrows towards the collars.
A sealant may be interposed between the polymeric spacers and their respective inlet and outlet pipes.
Preferably the polymeric spacers anchor the casing to the inlet and outlet pipes.
The polymeric spacers may be made from polytetrafluoroethylene.
The housing may include two sections secured to one another.
The two sections are preferably secured to one another by a connector. The two sections and the connector may have clip formations so that the two sections can be clipped to the connector. The connector may be a spacer to increase the length of the housing. Preferably the two sections are identical. Each section may include an integrally formed collar.
The polymeric casing is preferably made of a glass filled nylon.
The inlet and outlet pipes preferably form part of a continuous pipe which extends through the housing, with at least part of the continuous pipe located within the housing being perforated. Insulating material preferably surrounds the continuous pipe. The insulating material may be a continuous length of glass wool wrapped around the continuous pipe.
The silencer may however have a plurality of inlet and outlet pipes. The inlet and outlet pipes may be formed by a plurality of continuous pipes extending through the housing, with at least part of each continuous pipe located within the housing being perforated.